Sensitive Plant

Mimosa pudica, also known as the “sensitive plant”, “sleepy plant” or the “touch-me-not” is a type of creeping annual or perennial herb. The sensitive plant is native to Central and South America but can now be found in most tropical regions often as a problematic weed for many tropical crops and is currently considered to be one of the world’s worst invasive weeds! It is generally grown out of fascination for it’s touch sensitive leaves but it also has many uses in traditional medicines such as being an anti-depressant or sedative.

The sensitive plant undergoes two different types of nastic movements, nyctinastic and seismonastic movements. Nyctinastic movement is the closing of the leaves at night, likely to minimize water loss. Seismonastic movement is the quick closing of the leaves in response to physical stimuli or heat and is believed to be a way to protect itself from predators.

These movements occur due to the the loss of cell turgor pressure in the cell vacuole. When the plant is disturbed cells in the stems will release potassium ions which causes a reduction in water potential around neighboring cells causing water to diffuse out losing turgor pressure and resulting in cell collapse.